Methods of forming cutting elements by removing metal from interstitial spaces in polycrystalline diamond

Abstract

Methods of forming a cutting element include immersing at least a portion of a volume of polycrystalline diamond in a liquid electrolytic solution, applying a voltage between the polycrystalline diamond and a cathode in contact with the liquid electrolytic solution, and removing at least a portion of metal catalyst from interstitial spaces between adjacent diamond grains. The polycrystalline diamond includes interbonded diamond grains and metal catalyst particles in the interstitial spaces between adjacent grains of polycrystalline diamond material. Some methods include forming a barrier over a portion of a volume of polycrystalline diamond and transferring at least a portion of the metal catalyst from a portion of the polycrystalline diamond not covered by the barrier to a liquid electrolyte. Some methods include encapsulating a volume of polycrystalline diamond in a barrier and selectively removing a portion of the barrier from a first portion of the volume of polycrystalline diamond.

Description

FIELD[0001]The present disclosure relates generally to methods for removing metal from interstitial spaces in bodies of polycrystalline diamond, to cutting elements formed using such methods, and to tools for use in earth-boring operations, such as rotary drill bits, that include such cutting elements.BACKGROUND[0002]Earth-boring tools for forming boreholes in subterranean earth formations, such as for oil and gas extraction, carbon dioxide sequestration, etc., often include a plurality of cutting elements secured to a body. For example, fixed-cutter earth-boring rotary drill bits (also referred to as “drag bits”) include cutting elements fixed to a bit body of the drill bit. Earth-boring tools include, but are not limited to, core bits, bi-center bits, eccentric bits, hybrid bits (e.g., rolling components in combination with fixed cutting elements), roller cone bits, reamer wings, expandable reamers, and casing milling tools. As used herein, the terms “earth-boring tool” and “drill...

AI Technical Summary

Benefits of technology

The patent text describes methods for making cutting elements by immersing polycrystalline diamond in a liquid electrolytic solution and applying a voltage to remove metal catalyst from the spaces between diamond grains. A barrier is formed over a portion of the diamond to remove the metal catalyst from that area. The technical effects include improved cutting performance and reduced wear of the cutting elements.

Problems solved by technology

The presence of the metal solvent catalyst in the interstitial spaces within the polycrystalline diamond may lead to thermal degradation of the polycrystalline diamond commencing at about 400° C. due to differences in the coefficients of thermal expansion (CTEs) of the diamond and the catalyst.

However, removal of substantially all of the catalyst from the polycrystalline diamond may render the polycrystalline diamond less tough and less resistant to fracture, which may be particularly undesirable in certain drilling applications.

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